Linear guides (motion guide devices) are provided with a track rail, a slider block, and halls (or rollers). Circulation paths are formed between the track rail and the slider block. As the balls circulate (roll) in these circulation paths, the track rail and the slider block conduct a relative motion (movement).
A drive source of the linear guide includes a ball screw, a wire, a belt, a linear motor, and so on. For example, when the drive source is the ball screw, the wire, or the belt, semi-closed control based on a stepping motor is generally used. However, when positioning precision higher than in the related art is required, it is necessary to install a linear encoder to use closed control based on this linear encoder.
For example, when the drive source is the linear motor, a relative position. between a magnet section installed along a track rail and a coil section installed in a slider block is detected. To this end, an encoder scale of a linear encoder is installed on the track rail, and a sensor of the linear encoder is installed on the slider block.
To reliably detect the relative position between the magnet section and the coil section, the linear encoder should be accurately installed on the linear guide. However, it is not easy to accurately install the linear encoder added afterward on the linear guide. Therefore, it is proposed to previously dispose the linear encoder at the linear guide.